[FIX] web_tour: tip not visible anymore on notebook header

Since commit: odoo/enterprise@e662ef3629
a 'div' wrapper was added around the notebook header.

The tip was not visible due to it's location in the wrapper with
'overflow: hidden'.

After this commit, the tip is appended to the ancestor of the wrapper
and so it's visible again.

addons/web_tour/static/src/js/tip.js

@@ -135,6 +135,7 @@ var Tip = Widget.extend({
             p = $location.css("position");
         } while (
             $location.hasClass('dropdown-menu') ||
+            $location.hasClass('o_notebook_headers') ||
             (
                 (o === "visible" || o === "hidden") &&
                 p !== "fixed" &&